<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
</head>
<body>
    <script>
        "use strict";
        var person = {
            name:'xt',
            id:'021219'
        };
//        Object.preventExtensions(person);
//        console.log(Object.isExtensible(person));
//        console.log(person.id);
//        delete person.id;
//        console.log(person.id)
//        person.id = '12345';
        Object.freeze(person);
        console.log(Object.isExtensible(person));
        console.log(Object.isSealed(person));
        console.log(Object.isFrozen(person));
        person.id='20101515';
    </script>
</body>
</html>